The investigation of damage to supply water pumps at the EPR reactor at units 3 of Finland’s Olkiluoto (OL3) has ended, according to owner-operator Teollisuuden Voima Oyj (TVO). According to the plant supplier Areva-Siemens consortium, electricity production will resume on 25 December at the earliest, and regular electricity production will now therefore start in February 2023. TVO said there are still uncertainties regarding the schedule.

TVO said more detailed investigations and root cause investigations of the impellers of the feed water pumps are continuing. “After the investigations are completed, a decision will be made to start the facility. The possible effects of the results on the schedule will be communicated as soon as the investigations are completed.” The plant supplier is obligated to complete the plant unit in accordance with the Plant Contract and settlement agreements," TVO added.

In October, TVO announced that damage had been discovered in the internals of the feedwater pumps located in the plant's turbine island during maintenance and inspection work. Ten days later, it said cracks of a few centimetres had been identified in all four of the feedwater pumps. Since then the schedule for restarting the plant has been deferred several times. The OL3 feedwater pumps are used to pump water from the feedwater tank into the steam generators. TVO has said the cracks detected in the pumps have no impact on nuclear safety.

OL3 attained first criticality on 21 December 2021 and was connected to the grid on 12 March. The 1600 MWe EPR was operated at full capacity for the first time in late-September. The Areva-Siemens consortium constructed the OL3 plant under a fixed-price turnkey contract. Construction began in 2005 various setbacks and delays mean the plant is now more than 10 years behind the original schedule and significantly over budget. Once regular electricity production has started, OL3 will produce about 14% of Finland's total electricity consumption.

Image: Olkiluoto 3 will resume electricity production at the end of December (courtesy of TVO)